The monitoring of communication networks often involves the use of remote monitor probes sending back report data to a central measurement station. It is convenient to send the report data back over the same network as is being monitored; however, in doing so, there arises the possibility that the report data stream can affect the operation of the network in a way that invalidates the measurements being made. In many cases, such an adverse effect will be avoided or lie within acceptable bounds if the data rate of the report stream is sufficiently low.
A number of techniques exist for keeping the reporting data rate down. For example, the monitor probes can be arranged to effect initial processing of the measurement results, the results of the processing (such as various statistical measures) then being reported back; this approach is, however, only possible where details of each event of interest do not need to be reported. Another possiblility is for the monitor probes to act on a random sampling basis, reporting only some of the events of interest; this latter approach by its very nature makes it impossible to control exactly which event instances are detected (only event types) so that a particular event instance cannot be tracked across a network.
It is an object of the present invention to provide a way of controlling the report-stream data rate of monitoring apparatus that does not suffer from the above-mentioned drawbacks.